1. Field
The present general inventive concept relates to an electrophotographic toner and a method of preparing the electrophotographic toner.
2. Description of the Related Art
Developers to make electrostatic images or electrostatic latent images visible in an electrographic process or an electrostatic recording process may be classified into two-component developers and one-component developers. Two-component developers include toner and carrier particles, while one-component developers consist essentially of toner. One-component developers may be further classified into magnetic and nonmagnetic developers. In order to increase the fluidity of toner, nonmagnetic one-component developers often contain a fluidizing agent, such as colloidal silica. Typically, toner also includes coloring particles obtained by dispersing a colorant, such as carbon black, or other additives, in latex.
Methods for preparing toner include pulverization and polymerization processes. For pulverization processes, toner is obtained by melting and mixing a synthetic resin with a colorant, and optionally, other additives. The pulverized toner undergoes classifying until the particles of a desired size are obtained. In contrast, polymerization processes provide toner by uniformly dissolving or dispersing a colorant, a polymerization initiator and, optionally, various additives, such as a cross-linking agent and an antistatic agent, in a polymerizable monomer. The polymerizable monomer composition is then dispersed in an aqueous dispersive medium, which includes a dispersion stabilizer, using an agitator to shape minute liquid droplet particles. The temperature of the composition is subsequently increased, and suspension polymerization is performed to obtain polymerized toner having coloring polymer particles of a desired size.
Toner used in an imaging apparatus is obtained by pulverization. However, for pulverization processes it is difficult to precisely control the particle size, geometric size distribution, and the structure of toner. Thus, it is difficult to separately control the major characteristics of toner, such as charging characteristics, fixability, flowability, and preservation characteristics, using these processes.
Recently, polymerized toner has become increasingly used, due to a simpler manufacturing process, which does not require sorting the particles, and the ease of controlling the size of the particles. When toner is prepared through a polymerization process, polymerized toner having a desired particle size and particle size distribution can be obtained without pulverizing or sorting. In order to control uniformity of particle size and shape of toner in a polymerization process, an agglomeration process for preparing agglomerated toner may be used through the use of a metal salt such as MgCl2, and the like, or a polymeric material such as polyaluminum chloride (PAC).
By using a metal salt-based agglomerating agent it is possible to reliably control the particle size and particle size distribution of toner or to form a capsule structure with a shell, which is practically applied. However, it is still difficult to uniformly control the particle size and shape of toner. Typically, the particle size above a middle point of the particle size distribution of toner is highly controllable; however, smaller toner particles below the middle point of the particle size distribution tend to be more spherical than desired, and may cause problems in blade cleaning during electrophotographic processes.
To ensure both high gloss and a wide fusing latitude of toner, the agglomerating process may be controlled to form a capsuled toner structure, which ensures that a colorant and a releasing agent are not exposed to the surface of the toner, thereby improving charging uniformity, flowability, and thermal storage stability.
However, black toner still has problems with the use of carbon black colorant, in terms of image quality and transfer controllability. To address these problems, controlling the distribution of the colorant in the inside of a toner particle is required to improve image quality.